A character recognition technology such as an OCR (Optical Character Recognition) is known. The character recognition technology refers to a technology of converting the characters recorded in image data as imaged data into character codes (text data).
In many cases, in addition to the images of the characters to be recognized, image other than the characters of the recognition object is also included in image data. For example, apart from the characters (e.g. amount and commodity name) desired to be recognized, even ruled lines and a background color are also included in a business form. Moreover, besides answer characters, even a problem statement in which text data is considered to already exist is also included in a test paper.
The accuracy of character recognition is lowered if a great number of images needing no character recognition are included in image data.